With continued regulatory pressure there is a growing need to produce more environmentally sustainable replacements for refrigerants, heat transfer fluids, foam blowing agents, solvents, and aerosols with lower ozone depleting and global warming potentials. Chlorofluorocarbon (CFC) and hydrochlorofluorocarbons (HCFC), widely used for these applications, are ozone depleting substances and are being phased out in accordance with guidelines of the Montreal Protocol. Hydrofluorocarbons (HFC) are a leading replacement for CFCs and HCFCs in many applications; though they are deemed “friendly” to the ozone layer they still generally possess high global warming potentials. One new class of compounds that has been identified to replace ozone depleting or high global warming substances are halogenated olefins, such as hydrofluoroolefins (HFO) and hydrochlorofluoroolefins (HCFO). The HFOs and HCFOs provide the low global warming potential and zero or near zero ozone depletion properties desired.
Because of the presence of alkene linkage it is expected that the HFOs and HCFOs will be chemically unstable, relative to HCFCs or CFCs. The inherent chemical instability of these materials in the lower atmosphere results in short atmospheric lifetimes, which provide the low global warming potential and zero or near zero ozone depletion properties desired.
U.S. Pat. No. 6,013,846 discloses azeotropes of HF and 1233zd and methods for separating such azeotropes from mixtures of HF and 1233zd which are HF rich or 1233zd rich. The method comprises treating a mixture rich in HF relative to the azeotrope of 1233zd and HF in a distillation (rectification) column to obtain a distillate containing the azeotrope and a bottoms product of relatively pure HF